Add type predicate to Boolean (BooleanConstructor)

[KSXGitHub]

Suggestion

Add an overload to Boolean defintion

 interface BooleanConstructor {
 new(value?: any): Boolean;
- <T>(value?: T): boolean;
+ <T>(value?: T): value is Exclude<T, false | null | undefined | 0 | ''>
 readonly prototype: Boolean;
 }

playground

Use Cases

Array.filter

declare const actions: Array<(() => void) | null | undefined>
actions.filter(Boolean).forEach(act => act())

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

[MartinJohns]

Duplicate of #31164, #24063, #16655. Was implemented by #29955, and broken by #31515.

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.